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I have a 08 crf450x that I believe I might has a bad ICM.I noticed that the taillight wasn't working.So after doing some research online and some testing on it I Think that the ICM might be bad.I have a few questions about it and wondering if anyone who has first hand knowledge on this problem could help me sort it out.So my questions are,what actually causes this?, and what is the solution? Note: the bike does have the factory fender with the tail light in it,both stock.I have power at the black pigtail wire all the time , running or not. With the engine running I touched the grey ground wire from the tail light to the frame and the light came on. So at this point I’m not really sure what is bad or how to fix it.Any help with this would be greatly appreciated.

It might not be worth the effort to determine why it has failed. Most replace it with this and add the hydraulic brake switch so they have both a running light and a brake light:

https://www.crfsonly.com/catalog/produc ... ts_id/1350

Ken

Ken,Thanks for the reply.I did go ahead and order a new ICM. I was hoping to learn some reasons that causes this problem in order to prevent the same problem and possibly damage the new one.I'm a little nervous about plugging the old tail light wires into the new ICM . I'm thinking I should just replace the tail light too..? just to be on the safe side. At $170. for the ICM.

I misunderstood what you are asking. For some reason I read ICM as the integrated circuit board of the tail light. My apologies. I doubt the ICM was causing the light issue. It's pretty easy to test the light with just direct leads from the battery.

Ken

Ken, no problem. Thanks for the reply. I did test the tail light and it works. It's looking like my problem is within the Ignition control module. The grey wire (ground) coming out of the ICM is not doing it's job.I'm new to this site and I was just looking to see if anyone else had encountered this same problem.And gain some knowledge in sorting it out.Thanks again.

That's interesting. This is a first for me hearing of this specific issue.

Ken,
I have read it in the forums before where the tail light not working was an issue caused by ICM fault. Post id 331196 found it after quick search "tail light".
Make a good sticky.

Here is a final update (this is for future people with an ICM issue..).

A new ICM fixed the brake light. In conclusion, here is how to verify a bad ICM quite easily. Disconnect the ground wire connected to the ICM module (typically a bullet style, should be able to pull apart). Touch the ground wire to any part of the chassis, and if the light turns on you have a bad ICM.

This works because CRF450x (2005-2014, at least) uses a ground interruption to turn on/off the tail light. If your ICM is bad, you have no ground.

Thanks Ray,that's good to know. i'm waiting for the new ICM to ship.I will post a update when I get the new one installed. I still don't know what would cause the ICM to fail.Is something bad on the tail light ? a resister perhaps? We'll see.I went ahead and got a new tail light just to be on the safe side. I plan on opening up the old one to see if there is anything unusual. I would like to know so I can prevent this from happening again in the future.Those ICM's are expensive!